Comparison of Two Posterior Minimally Invasive Approaches for Odontoid Fractures: Midline Nuchal Ligament Approach vs. Paramedian Muscle-Splitting Approach.

objectiveThe posterior minimally invasive approaches for odontoid fractures include the midline nuchal ligament approach (MNLA) and the paramedian muscle-splitting approach (PMSA). However comparative data on their anatomical characteristics and clinical efficacy remain scarce to date. The objective of this study is to determine the differences in anatomy and clinical outcomes between the MNLA and the PMSA for reduction and temporary internal fixation of odontoid fractures.

methodsThis retrospective analysis focused on 31 patients with odontoid fractures from February 2021 to December 2023. Among them,16 patients underwent PMSA and 15 patients underwent MNLA. Various parameters were compared between the two groups, including operation time, intraoperative blood loss, postoperative complications, edema rates of cervical posterior muscles, the range of motion in rotation of C1-C2, patient satisfaction, Visual Analogue Scale score for neck pain, axial symptom scores, and neck disability index. Additionally, an anatomical study was performed; the PMSA and the MNLA were simulated on six fresh cadaveric specimens to compare the anatomical differences in surgical exposure between the two approaches.

resultsIn the clinical study, both groups successfully achieved fracture healing. Compared with the PMSA group, the MNLA group had several advantages, including shorter operative times, lower intraoperative blood loss, and a lower edema rate of posterior cervical muscles. However, similar results were observed between the two groups in terms of the range of motion in rotation of C1-C2, patient satisfaction, Visual Analogue Scale score for neck pain, axial symptom scores, and neck disability index at the last follow-up. In the cadaveric study, we found the trapezius-splenius capitis interface and the course of the greater occipital nerve (GON) varied significantly and the GON was present in the surgical field in 2 of 6 specimens in the PMSA, which brought difficulties for the surgical operation. In contrast, the MNLA, using the spinous process of C2 and the obliquus capitis inferior (OCI) as anatomical landmarks, provided a simpler surgical procedure and easier exposure.

conclusionBoth the MNLA and the PMSA demonstrated favorable clinical outcomes for the treatment of odontoid fractures. However, compared with the PMSA, the MNLA, using the spinous process of C2 and the OCI as anatomical landmarks, offers advantages of the stability of the surgical procedure, easy exposure, and reduced iatrogenic damage to the cervical posterior muscles and GON.